The present invention relates to an x-ray computed tomography apparatus for successively acquiring images of a plurality of slices of a given patient body and time-serially displaying the acquired images. The present invention also relates to an x-ray computed tomography apparatus which has a detector consisting of a plurality of arrays, reconstructs a plurality of images on the basis of detector data within a shorter period of time than the time required per scan, and displays the reconstructed images in real time.
Multi-slice CT is known as CT that can simultaneously reconstruct a plurality of tomographic images (the number of which does not always correspond to the number of detector arrays) within a shorter period of time than the time required per scan, and can display them approximately in real time (CT fluoroscopy).
In so-called conventional single-slice CT, only one tomographic image can undergo fluoroscopy. However, in multi-slice CT, a plurality of images (plurality of slices) can undergo CT fluoroscopy at the same time. In CT scan, tomographic images are displayed approximately in real time.
Since multi-slice CT fluoroscopy allows to observe a plurality of tomographic images at the same time, it is effective for various diagnoses, such as deviation detection of a biopsy needle in, e.g., biopsies and the like.
For example, in conventional multi-slice CT having a multi-slice detector consisting of three detector arrays, X-rays (radiation) radiated by an X-ray tube are collimated by a precollimator to a thickness corresponding to three slices. The collimated X-rays are transmitted through a patient body and then enter the multi-slice detector. Images corresponding to the individual detector arrays are independently displayed on a display.
During centesis procedures or the like, the operator of a centesis needle stands near a gantry, and works with the needle while observing a display equipped near the gantry.
The conventional X-ray computed tomography apparatus that allows multi-slice CT fluoroscopy suffers the following problems.
(1) Problem of Image Display Order
A case will be examined below wherein images reconstructed in correspondence with detector arrays 1, 2, and 3 are displayed in the order of images 1, 2, and 3 from the left, as shown in FIG. 50. As shown in FIG. 51, when the observer stands at position A, since the actual order of tomographic images in the slice direction when viewed from the observer matches the display order on the display, the observer can manipulate the centesis needle without any problems.
However, when the observer is located at position B shown in FIG. 52, the actual order of tomographic images when viewed from the observer is opposite to the display order on the display. As a result, the observer must imaginarily re-arrange the images, and has hard time manipulating the centesis needle.
Not only in the centesis procedures but also upon normally observing fluoroscopic images, the observer often mistakes the order of images with respect to the patient position. In this example, the display is disposed near a patient. However, the same problem is posed for, e.g., a display placed on a console.
Also, the same problem is posed when the observer stands on the gantry side, as indicated by positions C and D shown in FIG. 52.
(2) Obverse/reverse Problem of Image
Furthermore, positions A and C of the observer in FIG. 52 are compared. The observer at position A observes a section of the patient as if he or she were seeing the patient from the bed side (a direction in which the top of the head of the patient is seen from his or her toe side). At this time, an image seen from the foot side (bed side) must be displayed.
On the other hand, the observer at position C observes a section of the patient as if he or she were seeing the patient from the head side. At this time, an image seen from the head side (gantry side) must be displayed. The same applies to positions B and D of the observer.
For example, in the centesis procedures, the observer must manipulate the centesis needle while considering whether the image displayed on the display is seen from the bed side or the head (gantry) side. The observer may mistake the centesis direction, resulting in inefficient and long centesis. Not only in the centesis procedures but also upon observing fluoroscopic images, a wrong diagnosis is likely to be made.
In multi-slice CT fluoroscopy, when reconstructed images are merely displayed in a line, since the observer is forced to simultaneously observe a large number of images, it becomes hard for him or her to quickly and adequately grasp the current circumstance. Especially, this problem becomes more conspicuous with increasing number of fluoroscopic images.
For example, in the centesis procedures, three images are displayed in a line, a centesis needle is inserted along the central image, and the images at the two ends are normally used in deviation detection of the centesis needle.
However, it is a considerable burden even on a skilled person to simultaneously observe three images in detail, and he or she cannot recognize deviation of the insertion route of the centesis needle in time. To prevent this, if the centesis is slowly done over a long period of time, not only the centesis time becomes longer but also the dose on the patient increases.
Therefore, a new mechanism that allows an appropriate and quick surgical procedure such as a centesis or the like using multi-slice CT fluoroscopy is conventionally demanded.
Also the following problem is posed.
In multi-slice CT fluoroscopy, when reconstructed images are merely displayed in a line, the individual images are inevitably displayed in a reduced scale, and the observer can hardly observe them in detail. For example, when three images are displayed in a line at the same time, the image size is reduced to ⅓ compared to a case wherein only one image is displayed.
Upon making a surgical procedure such as a centesis or the like, circumstantial observation is especially required near a target portion. If the operator mistakes the distal end position of the centesis needle, tissue which is not the target portion may be sampled in, e.g., biopsies.
Furthermore, in conventional multi-slice CT having a multi-slice detector consisting of three detection element arrays, as shown in FIG. 53, the dose on the patient becomes larger than single-slice CT fluoroscopy since the beam width is increased in the slice direction.
The present invention has been made in consideration of the above situation, and has as its object to provide an X-ray computed tomography apparatus for displaying images of a plurality of slices by appropriately setting the display order or the obverse/reverse side of images in accordance with the observation position or the like of the observer.
It is another object of the present invention to provide an X-ray computer tomography apparatus which allows an appropriate and quick surgical procedure such as a centesis or the like using multi-slice CT fluoroscopy.
It is still another object of the present invention to provide an X-ray computer tomography apparatus which can reduce the dose on a patient in multi-slice CT fluoroscopy.
According to the present invention, there is provided the following X-ray computed tomography apparatuses.
A first X-ray computed tomography apparatus according to the present invention comprises: a detection unit for detecting a transmitted X-ray beam which is emitted by an X-ray generation unit and transmitted through an object to be examined; a reconstruction unit for reconstructing a plurality of images associated with different slices of the object to be examined on the basis of detection data obtained by the detection unit; a display unit for displaying images reconstructed by the reconstruction unit in a line; and a display control unit for controlling the display unit to change a display mode of the images.
A second X-ray computed tomography apparatus according to the present invention comprises: a detection unit for detecting a transmitted X-ray beam which is emitted by an X-ray generation unit and transmitted through an object to be examined; a reconstruction unit for reconstructing a tomographic image of the object to be examined on the basis of detection data obtained by the detection unit; a display unit for displaying a plurality of tomographic images reconstructed by the reconstruction unit in a line; and changing means for changing the way the plurality of tomographic images line up in the display unit in accordance with a standing position of an observer with respect to the object to be examined.
A third X-ray computed tomography apparatus according to the present invention comprises: a detection unit which is constructed by a plurality of detection element arrays each having a plurality of detection channels in a slice direction, and in which the respective detection channels detect X-rays; a reconstruction unit for reconstructing tomographic images of an object to be examined in units of a predetermined number of detection element arrays on the basis of detection data detected by the detection unit; a display unit for displaying the tomographic images in units of a predetermined number of detection element arrays in a line; and a display control unit for controlling the display unit to display a first tomographic image of the plurality of tomographic images in a display mode different from a second tomographic image.
A fourth X-ray computed tomography apparatus according to the present invention comprises: an X-ray generation unit; a detection unit which is constructed by a plurality of detection element arrays each having a plurality of detection channels in a slice direction, and in which the respective detection channels detect X-rays emitted by the X-ray generation unit; a reconstruction unit for reconstructing tomographic images of an object to be examined in units of a predetermined number of detection element arrays on the basis of detection data detected by the detection unit; slice thickness changing means for setting a slice thickness of an image of interest of the tomographic images reconstructed by the reconstruction unit to be larger than a slice thickness of an image of non-interest; and a display unit for displaying in a line the tomographic images, the slice thicknesses of which have been changed by the slice thickness control means.
A fifth X-ray computed tomography apparatus according to the present invention comprises: a detection unit for detecting a transmitted X-ray beam which is emitted by an X-ray generation unit and transmitted through an object to be examined; a reconstruction unit for reconstructing a tomographic image of the object to be examined on the basis of detection data obtained by the detection unit; a display unit for displaying a plurality of tomographic images reconstructed by the reconstruction unit in a line; and a display control unit for displaying a first tomographic image having a first slice thickness at a substantially center of the display unit, and displaying a second tomographic image having a second slice thickness smaller than the first slice thickness at an end portion of the first tomographic image.
A sixth X-ray computed tomography apparatus according to the present invention comprises: an X-ray generation unit for generating X-rays; a detection unit which is constructed by a plurality of detection element arrays each having a plurality of detection channels in a slice direction, and in which the respective detection channels detect X-rays emitted by the X-ray generation unit; generation means for generating a tomographic image of an object to be examined by bundling data from the detection element arrays; and changing means for changing at least one of an incident width of an X-ray beam that hits the detection element arrays and the bundle of data during a scan period.
A seventh X-ray computed tomography apparatus according to the present invention comprises: an X-ray generation unit for generating X-rays; a detection unit which is constructed by a plurality of detection element arrays each having a plurality of detection channels in a slice direction, and in which the respective detection channels detect X-rays emitted by the X-ray generation unit; a reconstruction unit for reconstructing a tomographic image of an object to be examined on the basis of detection data detected by the detection unit; and an image processing unit for generating a differential image by differentially processing a specific image and at least one of a plurality of tomographic images reconstructed by the reconstruction unit.
An eighth X-ray computed tomography apparatus according to the present invention comprises: an X-ray generation unit for generating X-rays; a detection unit which is constructed by a plurality of detection element arrays each having a plurality of detection channels in a slice direction, and in which the respective detection channels detect X-rays emitted by the X-ray generation unit; a reconstruction unit for reconstructing a tomographic image of an object to be examined on the basis of detection data detected by the detection unit; and a threshold process unit for comparing a pixel value of at east one of a plurality of tomographic images reconstructed by the reconstruction unit with a predetermined threshold value, and generating a threshold image consisting of pixel values that have exceeded the threshold value.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.